Conventional examination equipment, for example, a probe device is provided with a loader section having a conveyance mechanism for conveying semiconductor wafers one by one and a prober section for continuously electrically inspecting the semiconductor wafers. The prober section is provided with a mounting block for delivering and receiving the semiconductor wafers to/from the conveyance mechanism one by one, a probe card disposed above the mounting block, and a test head for electrically interrupting a section between the probe card and a tester. The test head is fixed on a rotating shaft through a test head frame and a hinge and is structured so as to obtain, for example, a 180-degree turn between the probe device body and a maintenance area around the rotating shaft. Recently, the test head has become larger in size to weigh 600 to 800 kg. In many cases, a motor is used to turn such a test head as a heavy object. Japanese Patent Laid-Open Publication No. Hei 9-298224 discloses almost the same prior art as the foregoing conventional one.
However, in the case of such a structure where a motor and a gear support the weight of a test head as seen in conventional examination equipment such as a probe device, the gear for transmitting a driving force of the motor unavoidably becomes larger in size and the gear is apt to have a multi-stage structure, thus causing the equipment to be complicated and expensive. Furthermore, there are also the following problems: turning the test head around the enlarged gear makes it difficult to reduce the turning radius and requires an increase in an installation space for the probe device.